Department of Laboratory Medicine, Affiliated Hospital of Jining Medical University, Jining Medical University, 89 Guhuai Road, Jining, 272000, Shandong, People's Republic of China.
Institute of Forensic Medicine and Laboratory Medicine, Jining Medical University, Jining, Shandong, People's Republic of China.
Int J Clin Oncol. 2020 Dec;25(12):2055-2065. doi: 10.1007/s10147-020-01771-1. Epub 2020 Aug 26.
Cancer stem cells have been implicated angiogenesis of tumor and invasiveness, drug resistance in tumors. Yes-associated protein 1 (YAP) owns carcinogenic roles in various organs, but the role of YAP in cancer stem cells of gastric cancer (GC) remains unclear. In this study, we explored the function and mechanism of YAP in GC cancer stem cells.
MATERIALS AND METHODS, AND RESULTS: First, we confirmed that the expression of YAP mRNA and protein in GC tissues was higher than in adjacent tissues by RT-PCR, western blot and immunohistochemistry. Immunofluorescence staining of the GC tissues revealed that the region of YAP expression coincided with the region of expression of the cancer stem cell marker SALL4 but did not overlap with that of the epithelial marker cytokeratin 14 (CK14). Additional research revealed that spherical cells expressed relatively high levels of YAP protein, and YAP overexpression reinforced self-renewal and expression of stem cell markers in the GC cells. Knockdown the expression of YAP reversed this phenomenon. Second, we examined the expression patterns of lipocalin-type prostaglandin D2 synthase (L-PTGDS) and prostaglandin D2 receptor 2 (PTGDR2) in GC tissues and proved that there was negatively correlation between the expression of L-PTGDS and PTGDR2 and YAP in GC tissues. Finally, we confirmed that YAP inhibited the expression of L-PTGDS and PTGDR2 by gain- and loss-of-function experiments. Moreover, the overexpression of L-PTGDS and PTGDR2 suppressed the proliferation and self-renewal induced by YAP in vitro and reversed the pro-tumor effect of YAP in vivo.
Our results revealed a novel function of YAP and the mechanism underlying cancer stem cell regulation by YAP.
肿瘤干细胞被认为与肿瘤的血管生成和侵袭、肿瘤的耐药性有关。Yes 相关蛋白 1（YAP）在各种器官中都具有致癌作用，但 YAP 在胃癌（GC）肿瘤干细胞中的作用尚不清楚。在这项研究中，我们探讨了 YAP 在 GC 肿瘤干细胞中的功能和机制。
首先，我们通过 RT-PCR、western blot 和免疫组化证实了 YAP mRNA 和蛋白在 GC 组织中的表达高于相邻组织。GC 组织的免疫荧光染色显示，YAP 表达区域与肿瘤干细胞标志物 SALL4 的表达区域重合，但与上皮标志物细胞角蛋白 14（CK14）不重叠。进一步的研究表明，球体细胞表达相对较高水平的 YAP 蛋白，YAP 过表达增强了 GC 细胞的自我更新和干细胞标志物的表达。敲低 YAP 的表达则逆转了这一现象。其次，我们检测了 GC 组织中脂联素型前列腺素 D2 合酶（L-PTGDS）和前列腺素 D2 受体 2（PTGDR2）的表达模式，并证实 L-PTGDS 和 PTGDR2 的表达与 GC 组织中的 YAP 呈负相关。最后，我们通过功能获得和缺失实验证实了 YAP 抑制 L-PTGDS 和 PTGDR2 的表达。此外，L-PTGDS 和 PTGDR2 的过表达抑制了 YAP 体外诱导的增殖和自我更新，并逆转了 YAP 体内的促肿瘤作用。
我们的结果揭示了 YAP 的新功能以及 YAP 调节肿瘤干细胞的机制。
